Method of surface coating articles



March 20,- 192s.

c. M. BIGELow METHOD OF SURFACE COATING ARTICLES Filed Dec. 8, 1924 ,as'i Patented Mar. 26, .19218.

UNITED .STATES 'PATENT ifoFFijcE.

i chars n. naamw, or NEWTON, Massacnusnr'rs,

METHOD or sum-Aon coa'rnie Jin'rrcnns..4

Appliization led'De'cember lacquers, when feasible, in placeofvar-I '10nishes and in producing uniformity of fthickness of coating or filmingon 'anarticle or' surface, upon the first application 'of the materialor compound thereto, thereby eliminatin the loss of time heretofore reJquired to preparatory to `receiving subsequent "coats, in order toattain the proper thickness and uniformity thereof. f i It is a furtherobject of the invention to '20, coat articles or surfacesin such manneras to entirely eliminate runs, thin places, .and

so called' fatty edges, and to produce a `film of substantially uniformthickness and at an g appreciablyreduced cost, particularly as to labor,and in less time per given article orlsurface than has been possible inthe past. f

Primarily `this invention has ,for one of its objects encouragement inthe use of lac- `quers for protective. coating in innumerabl'e aoinstances where varnishes or similar compounds are now used andappliedatgreat cost of time, labor and materialand not always ina'satisfactory and durable manner.

It is also an object of this .inventionto suc- 85 cessfull'y andexpeditiously coat articles having irregular surfaces or contours, whichheretofore was not possible exceptingby the use of hand methods whereinhighly skilled labor was necessarily employed, and conse- 40 quentlypresent day requirements as t'o production andcostwere not attained. f

Another important object of the invention is to eliminate wastage ofcoating material during the application thereof, and to use` thevaporous gases arising from` the volatile coating material, or gaseshavingylike properties and derived .from other sources if need be, incarrying out a feature of theinvention. l l y,

In the drawing illustrating the preferred apparatus for practicing thepresent process,

Figure l is a vertical sectional view: of the apparatus; Fig. 2 is asideelevati/Qn of the right hand. .side of :the apparatus ry the articleafterS each coating,

s`,1924. serial Nausea?. i

Fig.`1;and Fig. .3 is a cross-section on the line 3 3 of Fig. 1.

.A In pract1ce,the preferred method of covy ering an article withlacquer, for instance,

" :is bydipping it into the compound and al vowing it to 4drain4thereinto, but it will be understood that in sofar as this invention is;.concerned, it is immaterial how the coating is applied, whether bydipping, brushing, or VV:SPm-lll f 4 i i It wi l. be further understoodthat -while `this"`in've'i1tion is intended to be used in coni n ectionwithy lacquers, its use is not to be limitedthereto' as it might be usedin connection lwith paints and varnishesor other materials which may beadaptable to its use.

. In carrying out the invention it is preferred to dip) the article inaftankcontain- 'ing lacquer, y mechanical means, and while the articleis. in the lacquer impart motion to it, the mechanical means tobe'employed and` the motion to be imparted depending 'upon fthe articleto be coated.

I't has been the practice in the past to dip articles into varnish andthe4 like and withdraw them into the surrounding atmosphere where-theywere permitted to drain into the dipping tank during which processcoagula-x tion or settin took place slowl i when varnish. was'- vuse andrapidly w en lacquers were used.

, This method did not include movement of` the article durin the dryingprocessA and consequently a umform'thickness of coating was not obtainedas runs occurred, thin places were evident, and the formation of vthinandfatty edges was therule.

. -In the'present instance, and preferablyby the use-o mechanical means,the motion iin-V parted totheA -article-during the dipping i thereof iscontinued when the article is withdrawn from the dipping tank, and is tobe such-'a motion as to' preventruns and thin places, and to preventexcessive 4iiows in any particular direction andV to cause a uniformi'tyof coating to gradually take place after the excess material surroundingthe -freshly di ped article has fallen away or dripped -t erefromregardless of the conytinuedmotion of the aticle. slt is-a'fact that thespeed of withdrawal of the article from the tank of coating or -`iliningmaterial to eat extent determines yshown inf the final thickness o thefilmk on' an article or surface, inasmuch as an article which has beenslowly withdrawn from the tank will have appreciably less materialadhering 4thereto than thesame article would have 1f withdrawn from thetank speedily.

In`view of the above it is considered a feature of this invention tocontrol, to a considerable extent, the inal film thickness of an articleby the speed or lack of speed of itswithdrawal froml the filmingmaterial.

' As is well known, lacquers dry very rapl] idly, and even when thefreshly dipped article is kept in motion as above referred to,l

after having been dipped. in lacquer, is suspended or maintained in anarea or zdne of vaporous gases which arise froml the lacquer tank, orthe vaporous gasesI formed by the evaporation of lacquer or any of theknown tliinners or solventsv of lacquer, for even an a extended periodof time, surface evaporation is veryv appreciably retarded, which actionconveniently serves a very useful adjunct to the present invention bypermitting a natural and unretarded diffusion of the sol.

vent below the surface of the coating'.

It has also been discovered that by simple mechanical means, not deemednecessary to show herein, such as an air excluding cover I placed on thelacquer tank, it was possible to retain, confine and concentrate thevaporous gas arising from thelacquer, and; put 1t to use as amoisteningor film surface evapora- Ition retarding agent for lacquer onan arti cle suspended in its zone during the automatic place finding ofthe said lacquer.

. until the upper limit of the `is reached, where-it is nil. i

Advantage has been taken of this condi-- Yaporous gases are heavier thanair and consequently seek a lower level, and 4when confined as justdescribed, its 'density and moistening power areY greatest adjacent ythesurface of the lacquer in the tank, gradually decreasing in moisteningpower and density gaszone or areation to the end that the fumes orvaporous gases given off `by the lacquerin the tank have been confinedand in some instances concentrated and put to valuable use in venientform of clamp surface of the lacquer in the tank to zero at a Yapparatus for practicing the present process,

10 represents a tank or chamber provided withscoveijs 12, 13v hinged andadapted to be opened up to a vertical position between successiveoperations of the present process, it being understood that the presentprocess operates as' a batch or intermittent process. The lower portionof thetank 10 comprises a dipping tank and into which a plurality 'ofarticles ierein shown as saw handles are `dip ed during the operation oftheprocess, asvill be described, to cover the articles with a coatingmaterial.` As herein shown, a plurality of they saw handles'aresupported y holding devices 15 comprising any con- A and the latter aremounted to rotate with a shaft 16 journalled in bearings 17 slidablevertically in guide- Ways 18 mounted upon the sides of the tank.V,Provision is made for iotating'the shaft 16, and as herein shown theshaftlG is pro- -videdwith a sprocket 20 which is adapted to mesh withthe links of an endless chain 22 passing over a lower sprocket 23'and'an upper sprocket 24. The lower sprocket 23 is driven from asuitable source lof power through the driving pulley 25 and countershaft 26, its rotation being controlled by a manually operated'clutcliindicated at 27 and providedwith an operating lever 28.

In practicing the present process the saw 'handles -or other articles tobe coated are first dip ed into a bath of coating material by rotatingthe shaft 16 when the latter is` in a position such yas is illustratedin Fig. 1,'.

closed operating chamber above the level of the liquid coatingbath andwithin which chamber the vapors of the volatile solvent or solventsofthe coating material are present due to the evaporation fronitneliquid coating bath and also from the articles being coated. Thesolvents, as is wellknown, are heavier than air, and consequently thedensity -or concentration of the solvent in .the

vapor space above the coating bath gradually decreases from the coatingbath toward the top of the tank, and in practicing theV present processprovi sion is made for slowly Irotating the dipped saw handles or otherarticles at successive stations or heights above the coating bath t'o`permit the coating material upon thel saw .handles orother articles todry'i'n contact -With successive portions of the atmosphere :Within thetank containing gradually decreasing proportions of the volatilesolvents. In this manner the rate of dryingof the coating material iscontrolled ,lso as to enablethe rotary movement of the articles at thesuccessive stations to distributethe coating material u pon thevarticles into a uniform lilm extending over all parts of the article.

. lAs herein shown, provision is made for manually raising the shaft 16into they successive stations illustrated in dotted line positions inFig. 1, While enabling theshaft to be rotated at each station.' For thispurpose v the bearing blocks 17 are as above stated mounted to slide, invertical guideways I18 and are connected by suitable cords 3Q to aWindlass 32, thereby permitting the bearing blocks 17'to be raised asthe Wi'Idlass is. Wound up. Provision is made for holding the bearingblocks 17 at the different stations, and for this purpose holding dogs34 'are provided and which are pivoted in levers 35 connected by a link36, and which holding dogs 34 are yieldinfgl held -into a position toengage the bottom o the block 17, as the latter is raised past theparticular dog, by a spring 38. When it is desired to lovverthe shaftwhen a fresh supply of saw handles or other articlesiare to be coated,the link 36J is depressed, throwing out the holding dogs 34 from thepath of the block 17.

It Will therefore be seen that in the present process the article isfirst dip'pe in the liquid coating material and then dried While beingrotated in contact with an atmosphere containing progressivelydecreasing proportions of the volatile solvent. After having been driedor substantially dried, thetank is opened by lifting the covers andthearticle removed, and at thelsame time .opportunity 1s afforded for thevapors containing the solventto escape, thus permitting a fresli supplyof air to be introduced into the chamvber or tank to dry the succeedingbatches of v saw handles or other articles.

The present process is particularly' designed for producing anabsolutelunifornr film or coating lupon irregular s aped obto Va steady and.approximately constant sie .a

.found somewhere'intermediate the extremes thereof and readily locatedby easily performed experiments and might be observed through glassforming part of the tank cover,

Vhen`operating under this condition the i article is allowed to remainin the chosen positon untilthe lacquer thereon has found its place anduniformity of thickness thereof has been' attained, whereupon it is`Withdrawn from the vapor and exposed to the atmosphere Where lit rapidlycongeals or sets providing this action has not beenaccom- -plishedduring its exposure to the vapor.

The invention contemplates the applicaion of protective coating of anykind that sol is adaptable to this method, and in any way bestsuited'for the occasion, ,or desires, and subjecting the article tomovement 4of some sort, Whether it be rotary, vibratory or reciprocatry,best suited/to accomplish the results required and subjecting-the coatedmoving article to vaporous'gases, which method may be modified byomitting the movement of the article during the process, as in manyclasses of Work it might be prohibitive and even unnecessary. 1

The invention also contemplates the application of coating material inany suitable manner andthe movement of the article during the dryingprocess and omitting the exposure to vaporous gases,. which in mostinstances may not be successfully dispensed with, but in othersmay notbe required to ac eomplish .the desired result.

It Will be understood that, as previously referred to, Lthe inventionmight be used vin connection with paints and varnishes, or othermaterials which may be adaptedto lts use itis of especial importance inthe rubber industry, particularlyin .the manufacture of thin rubbergoods/or hollow articles such vas gloves, nipples, bathing caps, and infact rubber goods of all kinds made up by dipping orV repeated dippingin a rubber 'or rub-- ber substitute solution, whether made on a form orcore, or as a permanent coating to an article. l e Having described theinvention I claim:

1.- The process ofsurface-'coating articles4 'with a. liquid coatingmaterial,containing a' volatile solvent which consists in dipping thearticle into a bath ofthe liquid coatingI material contained in thebottom of a chamber, closed during .thecoating operation, lifting thearticle fro'mthe bath andslowly rotatin vit at' a plurality of stationsspaced succee ian ing .distances fromv the bath wherebyfthe slowly'rotating article'is permitted to dryf 12 while being rotated -incontactv with latinos,- phere containing progressively decreamngproportions of they solvent, and thereafterk opening the receptacle toremove the article,

v 2.5,An intermittent 'process of surface-coatmg articles'witha liquid.coating f containing a volatile solventwhich'consists portions of thesolvent, and then 'opening in dipping the article into a bath of the1iqtile tank and removing the, dried coated aruid coating materialcontainedin the bttlcle.. v

tom of a chamber, closed during thecoating Signed by meat Boston, Mass.,this 4th 5 operation, and then removing the article and day of Dec.,1924.

rotating it until subst'antiall dry, inc0ntact with vapor 'containingecreasing prov CABLE M. BIGELOW.

